1. Field of the Invention
The present invention relates to a power allocation method and apparatus for providing a packet data service in a mobile communication system.
2. Description of the Related Art
There are third generation mobile communication systems, such as HSDPA (High Speed Downlink Packet Access) of 3GPP (3rd Generation Partnership Project) and 1×EV-DV (1× Evolution for Data and Voice) of 3GPP2 (3rd Generation Partnership Project 2), which provide a voice service and a high-speed packet data service in a mobile communication system at the same time.
The above-mentioned two systems provide a line service and a packet data service within the same frequency allocation (FA). Since the line service has different characteristics from the packet data service, there occurs the following problem in providing two different services within the same FA.
The line service generally refers to a real-time service, such as a voice service, a video service or so on, which is very sensitive to a delay. To lower transmission errors without the delay, this line service performs transmission power control on the transmission side (at the base transceiver station) so that reception power is to be maintained at a constant level.
By contrast, the packet data service refers to a non-real-time service, such as Internet access, file transmission etc., which is not as sensitive to the delay as the line service. Therefore, the packet data service controls transmission speed in order to increase data throughout in spite of delays.
The foregoing systems share resources of the base transceiver station, the transmission side, in order to provide the line and packet data services within the same FA. As a representative example, power of the base transceiver station is shared during provision of the line and packet data services.
During the power control for the line service as well as speed control for the packet data service, the total power which the base transceiver station is capable of supplying is shared. In other words, the base transceiver station allocates all the remaining power other than the power needed to provide the line service in order to provide the packet data service.
FIG. 1 is a graph explaining power allocation in a conventional mobile communication system.
Referring to FIG. 1, in the case where a base transceiver station has available peak power as indicated by PFULL and is in operation with a certain amount of power, ΔP1, allocated to a mobile station for the line service at a certain time, t1, when any mobile station begins to get the packet data service, namely, there is generated new packet data traffic, the power corresponding to ΔP2 is allocated to the mobile station making use of the packet data service.
To be more specific, when the new packet data traffic intended for transmission is generated, the conventional systems transmit the packet data traffic in such a manner that the power, ΔP1, of the base transceiver station is preferentially allocated to the line service, and then all the power, ΔP2, remaining after allocation to the line service is allocated to the new mobile station, which makes use of the packet data service.
As a result, the power, ΔP2, allocated to the mobile station making use of the packet data service forces mobile stations, which make use of the line service while the constant power control is currently performed, to incur tremendous increase in noise.
That is to say, this is responsible for allocating all the power remaining after the line service is provided to the mobile stations making use of the packet data service at once, and thus interference to which the mobile stations making use of the line service are subjected is to be increased tremendously. Of course, the base transceiver station copes with the tremendously increased interference by means of the power control for guaranteeing the quality of the line service. However, because it takes transmission power some time to reach a new equilibrium point by means of this power control, the line service is subjected to outage for that time. Consequently, this leads to a problem in that the quality of the line service deteriorates.
Particularly, the higher a ratio of using the wireless data as in a wireless application protocol (WAP) or a hypertext transfer protocol (HTTP) becomes, the more frequently such a problem is generated. Thus, there is a drawback in that performance of the system is greatly decreased.